It's been 18 months since the NFL Players Association and the league agreed to introduce human growth hormone testing to the game.

The distance between agreement and implementation has been far greater than expected, however.

Thursday at the NFL Scouting Combine, NFL senior vice president for law and labor policy Adolpho Birch accused the NFLPA of stalling. A week earlier, representatives of the players union expressed their distrust in NFL Commissioner Roger Goodell and said they want the right to appeal the science of the test.

Washington Redskins linebacker London Fletcher -- a 15-year NFL veteran -- has been vocal in his wish to begin HGH testing. During a Tuesday appearance on "NFL Total Access," Fletcher explained why he's not taking party lines.

"I want a clean game. I want to compete against guys that are doing it the right way," Fletcher said. "I'm banging with fullbacks, I'm chasing these running backs around and the field is not level. You hear stuff about these guys that are cheating the system, cheating to be able to perform well."

Fletcher told The Washington Post he believes more than 10 percent of NFL players currently use HGH. NFL Network analyst Darren Sharper contended the number was closer to 50 percent.